Remove declaration of unthrown OrmException

Change-Id: Icb2535b7f8681b08734bc3955ad598eeb79a4fab
diff --git a/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java b/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java
index 4bd1a6c..c4ef78e 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/automerger/DownstreamCreator.java
@@ -275,7 +275,7 @@
   }
 
   public String getOrSetTopic(int sourceId, String topic)
-      throws RestApiException, OrmException, ConfigInvalidException {
+      throws RestApiException, ConfigInvalidException {
     try (ManualRequestContext ctx = oneOffRequestContext.openAs(config.getContextUserId())) {
       if (isNullOrEmpty(topic)) {
         topic = "am-" + UUID.randomUUID();